Objectives are to develop scientific information and to advance materials technology in permanent adhesive bonding of protective coatings and composites to both dentin and enamel with a practicable method. Success in these objectives will result in less drilling, loss of tooth structure, and need for injections of local anesthetics. Much needed protective coatings of exposed root surfaces could prevent root decay and provide a quick, durable treatment for hypersensitive dentin. The experimental design is to make systematic comparisons of the effectiveness in adhesive bonding of chemical analogues of the compounds now known to give unprecedented strong bonding: an acidic solution containing NPG (N-phenylglycine) and a solvent solution of PMDM (the reaction product of hydroxyethyl methacrylate and pyromellitic dianhydride). Synthesis and evaluation of analogs that are predicted to function more effectively than NRG and PMDM will be used to test hypotheses relating to the spontaneous polymerization of the monomers by molecular species bound to the substrate surfaces. The model substrates will be human dentin and enamel, and the origination of free radicals by the experimental compounds will be identified using electron paramagnetic resonance spectroscopy. Pulse radiolysis techniques will augment this determination of conditions required for radical generation. Improved and standardized methods will be developed for testing adhesion to dentin and enamel in both tensile and shear stress orientations to allow for more decisive statistical comparisons.